Re: large memory allocation

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Tue, 1 May 2001 10:19:04 +0200
Message-ID: <tess7nq1476fb6@beta-news.demon.nl>

<213.74.48.226 [hopehope_123_at_yahoo.com]> wrote in message news:4UtH6.144086$47.2082010_at_news.bc.tac.net...
>
> Dear Oracle community,
>
> Sorry this is a newbie question.
> Is it possible to allocate large memory with oracle such as 30gb. and
> if it is possible how can affect the performance?
> Can i use that much memory as data caching?
>
> Kind Regards,
>
>
>
> ==================================
> Poster's IP address: 213.74.48.226
> Posted via http://nodevice.com
> Linux Programmer's Site

What were you planning? Running an in-memory database? That won't work due to Oracle's lru algorithms. Running untuned applications only? The guideline of Oracle (and my experience too) is that the SGA shouldn't exceed 1/3 of physical RAM. Otherwise excessive paging by the O/S will be the result.
Also, there would be a theoretical limit 2^32 -1 on 32-bit platforms, but I believe I have read the maximum is 4G.
And, I can't see why on earth you would need 3 G cache, other than for the reasons above. It won't help you a bit, and it would hurt performance.

Regards,

Sybrand Bakker, Oracle DBA Received on Tue May 01 2001 - 03:19:04 CDT